In general, as a method for displaying information such as a product name, a manufacture-maker name, and a lot mark of a plastic product or the like, a method such as a method for describing the information on a label appended to the product, or a method for directly incusing the information on the product, is included.
Meanwhile, methods for reading out information associated with the kind etc. of an information presenting substance in advance, by adding an information presenting substance to various kinds of target objects in advance and detecting fluorescence radiated by the information presenting substance (see; Japanese Unexamined Patent Publication Nos. 2002-332414 and 2002-336798) have been suggested.